/*
 * Copyright 2013 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package io.netty.util.concurrent;

import io.netty.util.internal.logging.InternalLogger;
import io.netty.util.internal.logging.InternalLoggerFactory;

import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.AbstractExecutorService;
import java.util.concurrent.Callable;
import java.util.concurrent.RunnableFuture;
import java.util.concurrent.TimeUnit;

/**
 * Abstract base class for {@link EventExecutor} implementations.
 */
public abstract class AbstractEventExecutor extends AbstractExecutorService
        implements EventExecutor
{
    private static final InternalLogger logger = InternalLoggerFactory
            .getInstance(AbstractEventExecutor.class);

    static final long DEFAULT_SHUTDOWN_QUIET_PERIOD = 2;

    static final long DEFAULT_SHUTDOWN_TIMEOUT = 15;

    private final EventExecutorGroup parent;

    private final Collection<EventExecutor> selfCollection = Collections
            .<EventExecutor> singleton(this);

    protected AbstractEventExecutor()
    {
        this(null);
    }

    protected AbstractEventExecutor(EventExecutorGroup parent)
    {
        this.parent = parent;
    }

    @Override
    public EventExecutorGroup parent()
    {
        return parent;
    }

    @Override
    public EventExecutor next()
    {
        return this;
    }

    @Override
    public boolean inEventLoop()
    {
        return inEventLoop(Thread.currentThread());
    }

    @Override
    public Iterator<EventExecutor> iterator()
    {
        return selfCollection.iterator();
    }

    @Override
    public Future<?> shutdownGracefully()
    {
        return shutdownGracefully(DEFAULT_SHUTDOWN_QUIET_PERIOD,
                DEFAULT_SHUTDOWN_TIMEOUT, TimeUnit.SECONDS);
    }

    /**
     * @deprecated {@link #shutdownGracefully(long, long, TimeUnit)} or
     *             {@link #shutdownGracefully()} instead.
     */
    @Override
    @Deprecated
    public abstract void shutdown();

    /**
     * @deprecated {@link #shutdownGracefully(long, long, TimeUnit)} or
     *             {@link #shutdownGracefully()} instead.
     */
    @Override
    @Deprecated
    public List<Runnable> shutdownNow()
    {
        shutdown();
        return Collections.emptyList();
    }

    @Override
    public <V> Promise<V> newPromise()
    {
        return new DefaultPromise<V>(this);
    }

    @Override
    public <V> ProgressivePromise<V> newProgressivePromise()
    {
        return new DefaultProgressivePromise<V>(this);
    }

    @Override
    public <V> Future<V> newSucceededFuture(V result)
    {
        return new SucceededFuture<V>(this, result);
    }

    @Override
    public <V> Future<V> newFailedFuture(Throwable cause)
    {
        return new FailedFuture<V>(this, cause);
    }

    @Override
    public Future<?> submit(Runnable task)
    {
        return (Future<?>) super.submit(task);
    }

    @Override
    public <T> Future<T> submit(Runnable task, T result)
    {
        return (Future<T>) super.submit(task, result);
    }

    @Override
    public <T> Future<T> submit(Callable<T> task)
    {
        return (Future<T>) super.submit(task);
    }

    @Override
    protected final <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value)
    {
        return new PromiseTask<T>(this, runnable, value);
    }

    @Override
    protected final <T> RunnableFuture<T> newTaskFor(Callable<T> callable)
    {
        return new PromiseTask<T>(this, callable);
    }

    @Override
    public ScheduledFuture<?> schedule(Runnable command, long delay,
            TimeUnit unit)
    {
        throw new UnsupportedOperationException();
    }

    @Override
    public <V> ScheduledFuture<V> schedule(Callable<V> callable, long delay,
            TimeUnit unit)
    {
        throw new UnsupportedOperationException();
    }

    @Override
    public ScheduledFuture<?> scheduleAtFixedRate(Runnable command,
            long initialDelay, long period, TimeUnit unit)
    {
        throw new UnsupportedOperationException();
    }

    @Override
    public ScheduledFuture<?> scheduleWithFixedDelay(Runnable command,
            long initialDelay, long delay, TimeUnit unit)
    {
        throw new UnsupportedOperationException();
    }

    /**
     * Try to execute the given {@link Runnable} and just log if it throws a
     * {@link Throwable}.
     */
    protected static void safeExecute(Runnable task)
    {
        try
        {
            task.run();
        }
        catch (Throwable t)
        {
            logger.warn("A task raised an exception. Task: {}", task, t);
        }
    }
}
